640187707 has 4 divisors (see below), whose sum is σ = 640868976. Its totient is φ = 639506440.

The previous prime is 640187693. The next prime is 640187761. The reversal of 640187707 is 707781046.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 640187707 - 2¹¹ = 640185659 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 640187707.

It is not an unprimeable number, because it can be changed into a prime (640187507) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 339223 + ... + 341104.

It is an arithmetic number, because the mean of its divisors is an integer number (160217244).

Almost surely, 2^640187707 is an apocalyptic number.

640187707 is a deficient number, since it is larger than the sum of its proper divisors (681269).

640187707 is an equidigital number, since it uses as much as digits as its factorization.

640187707 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 681268.

The product of its (nonzero) digits is 65856, while the sum is 40.

The square root of 640187707 is about 25301.9308946966. The cubic root of 640187707 is about 861.8581182925.

The spelling of 640187707 in words is "six hundred forty million, one hundred eighty-seven thousand, seven hundred seven".